Count Number of Nice Subarrays

Given an array of integers nums and an integer k, a subarray is nice if there are exactly k odd numbers in it.

Return the number of nice subarrays.

Example 1:

Input:  nums = [1,1,2,1,1], k = 3
Output: 2
Explanation: [1,1,2,1] and [1,2,1,1].

Example 2:

Input:  nums = [2,4,6], k = 1
Output: 0

Example 3:

Input:  nums = [2,2,2,1,2,2,1,2,2,2], k = 2
Output: 16

Constraints:

• 1 <= nums.length <= 50000
• 1 <= nums[i] <= 10⁵
• 1 <= k <= nums.length